Efficiency of integrated waveguide probes for the detection of light backscattered from weakly scattering media

A semianalytical model for light collection by integrated waveguide probes is developed by extending previous models used to describe fiber probes. The efficiency of waveguide probes is compared to that of different types of fiber probes for different thicknesses of a weakly scattering sample. The simulation results show that integrated probes have a collection efficiency that is higher than that of small-core fiber probes, and, in the particular case of thin samples, also exceeds the collection efficiency of large-core highly multimode fiber probes. An integrated waveguide probe with one excitation and eight collector waveguides is fabricated and applied to excite and collect luminescence from a ruby rod. The experimental results are in good agreement with the simulation and validate the semianalytical model.